1. Field of the Invention
The present invention relates to a vehicle seat and a manufacturing method thereof, and more particularly, relates to a structure of a unit in the vehicle seat.
2. Description of the Related Art
Conventionally, automobiles which have multiple rows of seats in its fore-and-aft direction and whose rearmost seats are foldable forwardly from an upright position have been developed. Such an automobile usually has cargo room for storing cargo behind the rearmost seats and can attain larger cargo room by folding the rearmost seats forwardly. This type of rear seats have been widely applied to sport-utility vehicles (SUVs), minivans having three rows of seats, and the like.
Numerous variations of structures and mechanisms for rear seats whose seat backs are foldable forwardly have been known in the art. The frame structure has variations such as a split rear seat arrangement in which there are a plurality of seats in the lateral direction and their frames are split, and a bench-style rear seat arrangement in which seats in the lateral direction are joined and their frames are configured integrally.
The angle adjustment mechanism for the seat backs of rear seats has variations such as a reclining mechanism in addition to the seat back forward folding mechanism, a seat back angle adjustment mechanism by manual operation, and a mechanism that adjusts the seat back angle of rear seats equipped with an electric hinge by an electric actuator. For example, Japanese Unexamined Patent Application Publication No. 2007-83780 (Nakaya) discloses a multi-functional rear seat having an electric device that can fold the rear seat forwardly and reverse (raise) it to an upright position by a remote switch at the rear gate or the driver's seat, as a matter of convenience.
These numerous seat variations make it possible to offer rear seats which meet the type of vehicle or the user needs. On the other hand, however, it has taken much time to design rear seats type-by-type so as to address the numerous variations. For example, the rear seat in the above-referenced Nakaya has a seatback angle adjustment mechanism which is mounted inside the seat back. Consequently, it has been necessary to design the seat back frame structure and the seat back angle adjustment mechanism for each type of the rear seats so that the design time has been long. Accordingly, it has been desired to shorten the time for designing rear seats with numerous seat variations.
Besides, it is preferable that the seat back of a rear seat be thinner to increase the volume capacity of the cargo room when the seat back is in an upright position or in a forward folded position. Accordingly, there is a limit of space for the seat back of a rear seat. The rear seat having an angle adjustment mechanism inside the seat back, as disclosed in Nakaya, has significant restriction on thinning the seat back.